gastrula


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gastrula

 [gas´troo-lah]
an embryo in the stage following the blastula stage; the simplest type consists of two layers of cells, the ectoderm and entoderm, which have invaginated to form the archenteron and an opening, the blastopore.

gas·tru·la

(gas'trū-lă),
The embryo in the stage of development following the blastula or blastocyst; in lower forms with minimal yolk, it is a simple double-layered structure consisting of ectoderm and endoderm enclosing the archenteron, which opens to the outside by way of the blastopore; in forms with considerable yolk, the configuration of the gastrula is greatly modified owing to the persistence of the yolk throughout the gastrulation process. In human embryos, the gastrula stage occurs in the third week as the embryonic disk becomes trilaminar.
Synonym(s): invaginate planula
[Mod. L. dim. of G. gastēr, belly]

gastrula

(găs′trə-lə)
n. pl. gastru·las or gastru·lae (-lē′)
An embryo at the stage following the blastula, after the movement of cells results in the formation of the three germ layers, ectoderm, mesoderm, and endoderm.

gas′tru·lar (-lər) adj.

gas·tru·la

(gas'trū-lă)
The embryo in the stage of development following the blastula or blastocyst formation; in the human embryo, the absence of yolk allows for a rapid, direct "putting in place" of the germ layers (ectoderm and endoderm), which are derived from the pluripotential embryonic disc.
[Mod. L. dim. of G. gastēr, belly]

gastrula

The stage in the development of an EMBRYO following the BLASTULA stage when the ECTODERM, ENDODERM and primitive GUT have developed.

gastrula

a stage in embryonic development in which the BLASTULA has invaginated, so giving rise to a two-layered embryo by a process of gastrulation. see ARCHENTERON.
References in periodicals archive ?
1B fertilization envelope Gastrula Elongated, 4 days Fig.
splendens desde la fecundacion hasta la eclosion (1), pasando por diversas etapas (cigoto, clivaje o blastulacion, gastrula, segmentacion y organogenesis, eclosion y estado larval), en esta investigacion insumio una duracion de 36,13 h.
Why does not FGF signaling activate ZicL expression in the brain cells before the gastrula stage?
Initiation of TDCPP exposures at 2.25, 10, and 24 hpf, as well as exposures in blastula (2.25-5 hpf), gastrula (5.25-10 hpf), segmentation (10-24 hpf), or pharyngula (24-48 hpf), did not enhance the toxicity of TDCPP compared with exposures during 5.25-96 hpf (data not shown).
Ingestion of these plants during gestation may cause anomalies in foetus (Jones, 1983) it is believed that embryo is injured during blastula and gastrula stages of development.
Most of these developmentally arrested embryos died during late blastula to early gastrula while some made it through gastrulation, but terminated development at the characteristic shield stage of development where an obvious anterior to posterior axis had formed.
The early embryo, at about 3 weeks' gestation (gastrula stage), is differentiated into three distinct cell layers, ectoderm, mesoderm, and endoderm.
In this context the (almost) anaerobic metabolism at blastula stage embryo could reflect the existence of multi-cellular organisms in the deep anoxic Earth while the transition to aerobic metabolism at gastrula could be related to the evolution towards tridermic organisms around 2 billion years ago.
A Colorado beetle has a better claim to suffer than a human gastrula.